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By Aresby
#37378 Hello everyone :D

I've got a Wemos D1 ESP8266 board that looks like an Arduino (size and layout wise) but isn't; it's a ESP8266 on an Arduino-sized board and is supposedly Arduino compatible (with a couple of caveats, like only having a single analog input available).

I've installed all the supporting software so I can use it with the Arduino IDE (1.6.7) and initially it seemed fine: I could set up a simple Wifi client to turn an LED on/off remotely via a browser, and can get the time from an NTP server. So far so good.

However, there is an anomaly. The simple BLINK program works backwards; that is, setting the pin to HIGH makes the LED go off and vice versa. Easy enough to 'fix' but what are the ramifications?

I only noticed this when I attempted to communicate with an MAX7219 to display a rolling message on an LED matrix - works as expected on a standard Arduino but causes an almost immediate reset (cause:4 :?: ) on the Wemos D1.

After hours of experimentation it seems the D1 has problems setting (some) output pins HIGH or LOW. It just resets. Scouring the internet proved less than fruitful because very few people have this actual board.

I've now ordered an ESP8266 MODULE to connect to my Arduino UNO to see whether it exhibits the same behaviour (HIGH/LOW reversed, crashing on MAX7219 comms).

In the meantime, does anyone have any experience with this WEMOS D1 board and can anyone understand what this weird behaviour is all about?

Sorry my first post is immediately demanding your attention but I've run out of ideas! :oops:
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By martinayotte
#38765 About LED reverse polarity, it is probably normal probably if LED is connected with GPIO "sink"mode instead of "source" mode, especially if this LED is connected on GPIO2 or GPIO0, since placing it in "source mode" will have the effect of pulling down the GPIO and therefore prevent proper boot process.

For the intermittent resets while using MAX7219, you probably need to explain the wiring you've done for it, and provide the piece of code that you use, many there is an obvious mistake in it each make the watchdog been triggered.
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By schufti
#38772 just for your information:

IDE 1.6.7 is known to have issues with ESP8266 board extension ...
if you want to use something newer than 1.6.5.r5 you can try arduino-nightly-windows-290915 ; I'm using it without any negative effects right now and it identifies itself as 1.6.6